DONETSK, Ukraine — Ukraine's government struggled to stay in control of the country's eastern regions as tensions flared Tuesday in three cities. While the government managed to recapture its regional headquarters and detain dozens of pro-Russian protesters in one city, it said "radicals" were keeping 60 people hostage and threatening them in another city.
Unknown "separatists" with weapons and explosives were threatening the hostages inside a security service branch in the city of Luhansk, the Ukrainian Security Service said in a statement Tuesday.
It was not clear who the hostages were or if they were security service employees. The building was seized Sunday by armed pro-Russian protesters.
Earlier Tuesday, Ukrainian authorities battled with pro-Russian protesters but regained control over a government building in Kharkiv, the country's second-largest city, evicting the protesters and detaining dozens.
In Donetsk, a city 250 kilometers (155 miles) further south, protesters dug in for their third day at the 11-story regional administration headquarters they captured on Sunday and began to declare their own parallel government.
Serhiy Taruta, the governor of Donetsk, scoffed at the shifting events in his city.
"I call this a theater of the absurd," he said. "It is just artists performing, but the main thing is that there is an ever-dwindling audience."
All three cities are in Ukraine's east, where hostility is strong toward the government that took power in February after the ouster of Kremlin-friendly President Viktor Yanukovych. Even though Ukraine's interim authorities have achieved some success in quelling unrest that swept across eastern provinces Sunday, festering discontent threatens to undermine plans to hold a presidential election on May 25.
In Washington, Secretary of State John Kerry on Tuesday threatened Russia with tougher economic sanctions if it fails to back down from its involvement in Ukraine.